env: Pass additional parameters to the env lookup function

In preparation for the multiple environment support, let's introduce two
new parameters to the environment driver lookup function: the priority and
operation.

The operation parameter is meant to identify, obviously, the operation you
might want to perform on the environment.

The priority is a number passed to identify the environment priority you
want to retrieve. The lowest priority parameter (0) will be the primary
source.

Combining the two parameters allow you to support multiple environments
through different priorities, and to change those priorities between read
and writes operations.

This is especially useful to implement migration mechanisms where you want
to always use the same environment first, be it to read or write, while the
common case is more likely to use the same environment it has read from to
write it to.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/include/environment.h b/include/environment.h
index a2015c299a..a4060506fa 100644
--- a/include/environment.h
+++ b/include/environment.h
@@ -205,6 +205,14 @@ enum env_location {
 	ENVL_UNKNOWN,
 };
 
+/* value for the various operations we want to perform on the env */
+enum env_operation {
+	ENVOP_GET_CHAR,	/* we want to call the get_char function */
+	ENVOP_INIT,	/* we want to call the init function */
+	ENVOP_LOAD,	/* we want to call the load function */
+	ENVOP_SAVE,	/* we want to call the save function */
+};
+
 struct env_driver {
 	const char *name;
 	enum env_location location;